in that environment, it falls like snow. cnn's john zarrella is covering this from miami. just how big of a problem is this leak, and is it a safety concern for the crew at the iss? >> reporter: no, it's not. first thing we have to say is the crew was never in any danger with this. it is not a safety issue for the crew. but it's certainly a critical system issue they want to get fixed. you don't want ammonia coolant leaking out of the space station. they've had a similar problem in this very same area not long ago, but they weren't able to actually identify where it was exactly coming from or to be able to fix it. as you mentioned, they had been able to eyeball it this time, and they can see those tiny white flakes, which is ammonia, leaking from what they believe is around a pump area on the space station. what they decided to do was go out right away, very quickly get to the space walk. the reason they're doing it so quickly is because, once the ammonia leaks out from that area where it is, they won't be able to find it again because the pinprick hole, the size is so sma